This is a device for treating liquids which, due to either biochemical action or having chemicals added, form a floc that settles by gravity and where there is an advantage in the liquid to be treated, passing upwardly through this floc blanket. The partially treated liquid then passes upwardly through a filter that retains some of the remaining suspended solids in the liquid.
The filter is designed to filter liquids on a continuous basis and is capable of operating in two modes. Firstly, the filtering or treatment mode where the liquid passes continuously upwardly through the floc blanket, through a filter element and then outwardly through a discharge spaced above the filter element. Secondly, when it is desired to cleanse the device, airlocks situated between the main filter chamber and a chamber therebelow, are released thus allowing the filter to empty downwardly carrying with it the sludge, floc, etc., into the chamber therebelow where upon it may be discharged therefrom with the liquid continuing to flow into the main chamber to flush same until it is changed back to the filtering mode. As the hydraulic head above the filter element flows downwardly through the filter element, it cleanses same in a back flushing action.